Utilizing a model of thyroid transplantation in mice, the Cr51 release from a mouse tumor line, and a Coulter Counter equipped with a channelizer, we plan to investigate the following problems: (1) The mechanism of stimulation and suppression of cytolytic lymphocytes by macrophages and tumor cells; (2) The elimination of passenger leucocytes from allograf f the sequence involved in the binding sites. To achieve this goal homogeneous antibody preparations are being studied rather than the heterogeneous preparations which have been studied in the past. Studies are being done by subjecting homogeneous antibodies to controlled chemical alterations so that reactions taking place in the binding region can be distinguished from reactions taking place elsewhere on the molecule. The amino acid residues composing the binding region are being determined, as well as the position of these residues in the polypeptide chains which make up the protein. Surface features of immunoglobulin are being determined by determining the relative reactivity of identifiable residues with particular chemical reagents. The degree ?f exp?su?e ?? cye su?f~ce ?f cye m??ecu?e is c~k e? c? se ~ fu?cci?? ?f cye ?e~ccieicy, BZBLZOGRA7HZT RVWVRVNTVB: B,2, Be??, 1, 4i??f~u~ ~?u D, 7?essm~?, Zmmu??x??su?i?s ?? Tu?cu?eu Hum~? Lympy?cyces, Zmmu???, T?mmu?,, 4:14R, 1R7N, A,L, G??ssse?x ~?u D, 7?essm~?, A?cis?uies Ax~i?sc cye A?ipy~cic Bucci?y? G??up: 7?ese?ce ?f Ty??si?e ~?u ~ 7?siciee Ty~?xe i? cye Bpecific T?msi?i?x Bice, Zmmu??cyemisc?y, 12:4NL, 1R7N, The studies determine the current prevalence of viral respiratory diseases of specific etiology. The virus are characterized for antigenic composition. Host response and factors causing increased susceptibility and specific resistance are investigated in man and animals. Drugs with potential protective effects in man are studied for the mechanism of action and efficacy. BIBLIOGRAPHIC REFERENCES: Muldoon, R.L., Stanley, E.D., and Jackson, G.G.: Use and withdrawal of amantadine chemoprophylaxis during epidemic influenza A. Am. Rev. Resp. Dis., April 1976. Jackson, G.G.: Concepts in training, performance in practice. J. Inf. Dis. 131:485-490, 1975.